The present invention relates to a fuel injector.
From German published Patent Application No. 197 57 299, a fuel injector is described in which a fuel injection chamber is arranged downstream of a valve seat. For opening and closing the valve, an axially movable valve needle cooperates with the valve seat, the needle having a conical closing segment corresponding to the contour of the valve seat. Upstream of the valve seat, on the exterior periphery of the valve needle, a diagonally running swirl channel is provided. The swirl channel empties into an annular swirl chamber, which is formed between the valve needle and an external valve housing. From this swirl chamber, the fuel is conveyed to the valve seat. From the fuel injection chamber downstream of the valve seat, the fuel flows into an outlet opening, which begins slightly offset from the center of the base surface of the fuel injection chamber and runs downstream diagonally with respect to the valve longitudinal axis.
The fuel injector according to the present invention, has the advantage that in a particularly simple manner, a cost-efficient compensation is achieved for the unequal distribution of fuel in the spray to be spray-discharged arising in response to a chosen inclination of an outlet opening, towards the goal of an equal distribution of a spray that is diagonally spray-discharged. Using the fuel injector according to the present invention, very good atomization and very precise spray discharging of the fuel are achieved, e.g., directly into a cylinder of an internal combustion engine. A particularly uniform front of the spray-discharged spray is attained. In addition, it is avoided that individual streams in the spray have great speed and depth of penetration.
It is advantageous to achieve the above-mentioned compensation of the irregularity of the spray using an outlet opening, the central point of whose intake plane lies on the valve longitudinal axis, the intake plane thus having a central intake. In this manner, however, in response to the preselected small diameter of the valve seat in the area of its seat contact line, in order to avoid large hydraulic forces being exerted on the valve needle, relatively large diameters can be selected for the outlet opening, permitting a large flow of fuel. In comparison with the off-center solutions, flow-through dispersions can be better avoided.
In a particularly advantageous manner, swirling fuel is fed to the valve seat in the valve seat element over an extremely short flow route. This very short flow route is also guaranteed to the extent that the outlet opening begins immediately at the end of the valve seat surface, avoiding any collector spaces.
The disk-shaped swirl element has a very simple structure and can therefore be shaped in a simple manner. It is the task of the swirl element to generate a swirl or rotary motion in the fuel. Since the swirl element is an individual structural element, its handling in the manufacturing process should not give rise to any limitations.
In comparison to swirl bodies, which have grooves or similar swirl-generating indentations on an end face, it is possible, using the simplest of means, to create in the swirl element an interior opening area, which extends over the entire axial thickness of the swirl element and is surrounded by an exterior circumferential edge area.